Picciariello, Angela

KTH, School of Electrical Engineering (EES), Electric Power Systems.

2015 (English)Doctoral thesis, comprehensive summary (Other academic)

Abstract [en]

Energy policies in favor of a larger adoption of renewable energy sources for electricity production purposes and the significant progress of several renewable technologies are among the main drivers behind an increasing integration of distributed generation (DG) in distribution networks.

Two main complementary tools for an efficient integration of DG have been identified in this thesis: (i) a sound economic regulation of Distribution System Operators (DSOs) for taking into account DG-driven potential costs and accordingly remunerating DSOs, and (ii) network tariff design, in order to allocate network costs and re-distribute potential benefits to different grid users.

Distribution economic regulations vary from country to country with grid characteristics and regulatory customs. In order for Regulators to promote the integration of DG units according to policy objectives, the potential impact of DG on the different distribution costs needs to be analyzed and quantitatively assessed: in this thesis, these objectives are achieved by using a novel model that combines the technical characteristics of distribution grids with the regulatory details specific of each regulation.

Once computed, DSOs' total allowed revenue is allocated to different users' categories according to the adopted tariff structures. This thesis focuses on the challenges arising within the traditional paradigm of distribution tariff design when an increasing amount of DG is connected to the grids. In particular, the consequences of DG exemption from distribution tariffs and the application of load-tailored tariff schemes to DG are investigated, both from a qualitative and quantitative point of view; cross subsidies between consumers and DG owners are computed by applying a cost causality principle.

Identifiers

Public defence

Opponent

Brunekreeft, Gert, Professor

Jacobs university, Germany.

Supervisors

Söder, Lennart, Professor

KTH, School of Electrical Engineering (EES), Electric Power Systems.

Alvehag, Karin

KTH, School of Electrical Engineering (EES).

Note

The Doctoral Degrees issued upon completion of the programme are issued by Comillas Pontifical University, Delft University of Technology and KTH Royal Institute of Technology. The invested degrees are official in Spain, the Netherlands and Sweden, respectively. QC 20151009

Picciariello, Angela

Alvehag, Karin

Söder, Lennart

KTH, School of Electrical Engineering (EES), Electric Power Systems.

2012 (English)Conference paper, Published paper (Refereed)

Abstract [en]

Integration of distributed generation (DG) into distribution networks may affect many different factors, such as network reliability, voltage quality and network planning. Network regulation, therefore, is needed to provide the distribution system operators (DSOs) with fair business, meanwhile protecting the consumers and producers from any potential exploitation by the DSOs because of their monopoly situation. EU Member States have implemented different regulations, but there is no consensus yet as to what is the most appropriate mechanism for a successful and efficient integration of DG in distribution grids. This paper reviews the state-of-art of the regulatory frameworks for the integration of DG in some EU countries, and methods to model the regulation impact on DG integration in distribution systems. For each regulatory scheme, the main critical issues concerning DG integration are identified.

Abstract [en]

Increasing amount of distributed generation (DG) connected to distribution grids is likely to affect the operation of the grids themselves, for example by changing the magnitude and, in some cases also the directions, of the power flows in the networks. This can have different economic consequences on the Distribution System Operators (DSOs) depending on the different enforced network regulations. This paper proposes a method for how to calculate the incentive for DSOs to integrate DG into their grids. The calculation of this incentive is carried out for the Portuguese case. Only the operational aspects are considered to calculate costs and benefits for the DSO, including network tariffs, ancillary services costs, Operation and Maintenance (O&M) costs, and economic treatment of losses. The IEEE 34 Node Test Feeder is used to perform power flow analyses under different scenarios of DG penetration. The analysis shows that the Portuguese DSO would have an incentive to integrate a low level of DG penetration; in case of a higher level of DG penetration, however, this incentive would turn into a small disadvantage for the DSO. In both cases, the regulatory treatment of network losses turns out to be the relevant factor to determine such a result.

Place, publisher, year, edition, pages

IEEE, 2013

Series

International Conference on the European Energy Market, EEM, ISSN 2165-4077

Abstract [en]

The integration of distributed generation (DG) in distribution grids is one of the pillars of smart grid deployment. However, an increasing amount of DG connected to distribution grids is likely to affect the operation of the grids themselves, e.g., changing the magnitude, and in some cases the direction, of power flows. In order to perform the transition to a smart grid, it is therefore essential to have the distribution system operators (DSOs) involved in the process. However, being that the DSOs' business is controlled by regulators, regulation has a fundamental impact on the speed and the actual performance of DSOs' involvement in the transition toward a smart grid. Therefore, a method is needed to assess network regulation impact on DSOs' incentive to integrate DG into their grids. This paper proposes a new method for the calculation of such incentive, and the method has been applied on a case study to the Portuguese, Danish, and Swedish regulations for different scenarios of DG penetration. The focus is on DSOs' operational costs and revenues. The analyses indicate that DG has a different impact on DSOs business, depending on the different regulations, the most relevant aspects being the structure of customer tariffs and the regulatory treatment of network losses.

Abstract [en]

Due to the increasing amount of DG (distributed generation) in distribution grids, new challenges are arising in the distribution sector in many countries. Depending on the DG penetration, location, concentration, size and generation technology, the DG impact on network costs can be either negative or positive. These additional costs or benefits can be allocated to the DG owners through network tariffs. New cost allocation methodologies, based on a cost causation principle, are therefore required. This paper addresses several issues arising within network tariff design due to the integration of DG. Furthermore, it reviews the methodologies proposed so far to tackle those issues. Recommendations for setting up a new, cost causation-based, methodology are finally drawn.

Abstract [en]

An increasing amount of distributed generation (DG) can cause an increase or a decrease on distribution network costs. Tariff design is the main tool for allocating these costs to customers who own and operate DG resources. Currently, however, either DG units are exempt from paying distribution tariffs or they are subject to tariffs originally designed according to a traditional pricing model without DG in the grids, also known as load-based pricing. Partial recovery of the allowed distribution company revenue requirements or cross-subsidies between customers may ensue from such tariff arrangements. In this article, pricing, as represented by a combination of net metering and pure volumetric tariffs, is applied in the context of increasing DG. The paper presents a methodology where a Reference Network Model (RNM) is used to investigate the effect of this pricing scheme on the magnitude of cross-subsidies from consumers towards the so-called prosumers for a set of twelve simulations based on real-size networks in the U.S.For the considered scenarios, the analysis reveals substantial cross-subsidies from consumers toward prosumers. The degree of subsidy varies with the amount of DG connected to the grid and network characteristics. The rate of cross-subsidy tends to be higher for low-density grids. This paper contributes to the net metering literature with a quantitative assessment of cross-subsidies by comparing allocated payments to different actors with the costs they impose on the system, estimated through an RNM. Moreover, the paper proposed a tariff structure based on cost causality by proposing a cost-reflective, volumetric tariff approach through which aggregate load-driven and DG-driven network costs are accordingly allocated to loads and DG units.